I am using this birthday picker:

http://www.jqueryscript.net/time-clock/Customizable-Dropdown-Birthday-Picker-Plugin-with-jQuery.html

so I am adding it like this:

1. <div id="birthday"></div>

The birthday itself is not requited but I want to know how can I make the month required is the day was selected / the day required if the month was selected?

How can I do this please?

Thanks,

Jassim